The satan” (i.e., “the adversary”) in Job is a member of God’s divine court, not the devil of the New Testament. When this divine figure reported to God in Job 1, God asked him where he’d been. He reported that he had been “going to and fro on the earth, and from walking up and down on it” (Job 1:7). So his job was to see if people were obedient to God or not. God took the occasion of the report to brag on Job. He asks the satan, “Have you considered my servant Job, that there is none like him on the earth, a blameless and upright man, who fears God and turns away from evil?”
The adversary’s answer sets the rest of the book in motion and with it the famous suffering of Job. The adversary has an axe to grind and gets uppity. He challenges God’s reading of the situation: “Does Job fear God for no reason? Have you not put a hedge around him and his house and all that he has, on every side? You have blessed the work of his hands, and his possessions have increased in the land. But stretch out your hand and touch all that he has, and he will curse you to your face.” (Job 1:9–11). In essence, the adversary challenges God’s omniscience and authority—God doesn’t really know Job, and since he doesn’t, he has no right to praise him.
This is a challenge that God cannot let pass. God cannot just destroy the adversary for his arrogance. That would only eliminate the accuser, not answer the challenge. God’s reputation needs vindication. That is what the book of Job is really about.
The book of Job devotes a lot of space to presenting and evaluating a range of human responses to why Job is suffering and, ultimately, why the righteous suffer. The book doesn’t offer a resolution to this last question. The “answer” comes in an appearance of God in the whirlwind. Job sees clearly that he is not God and has to be silent. But consider the book’s conclusion. Job did not sin in his suffering. He does not curse God. In other words, his character shows that God was correct and the adversary was wrong. Job is therefore rewarded abundantly by God (Job 42:10–17). Although readers don’t get an answer to why the righteous suffer, they know that, at least in this case, it was to vindicate God. He does see, and he is sovereign. Like Job, we must trust God is good and knows what he is doing.